Roof structure and truss therefor



May 21, 1940. H, RUPPEL 2,201,504

ROOF STRUCTURE AND TRUSS THEREFOR Filed May 20, 1938 2 Sheets-Sheet 1 May 21, 1940. F. H. RUPPEL ROOF STRUCTURE AND TRUSS THEREFOR Filed May 20, 1938 2 Sheets-Sheet 2 Patented May 21, 1940 UNITED STATES ATENT OFFICE 2,201,504 ROOF STRUCTURE AND rnpss THEREFOR Frederick H. Ruppel, Pasadena, Calif. Application May 20, 1938, Serial No. 209,042

13 Claims.

The present invention relates to roof structures containing structural steel trusses andto the individual trusses per se.

In ordinary structural steel practice the steel trusses are supportedby wall columns spaced apart a considerable distance along the wall.

This spacing is ordinarily from '16 to perhaps 24 feet. The Wall between the columns supporting the trusses then becomes a filler wall sup-porting no direct vertical load except its own weight.

With the ordinary structural steel practice a large number of web members-is customarily used for the purpose of providing atop chord panel point wherever a'purlin' occurs. This practice is employed to minimize the cost of-relieving the top chord of a truss of bending stresses.

The present invention has for its general object to provide a structural steel truss and roof structure embodying the same which will eliminate iii any of the defects and limitations to the use of structural steel in roof structures.

More particularly, in accordance with'the present invention, I provide trusses, one or more chords of which are formed of webbed structural elements, preferably expanded I-beams, which are of light weight. These trusses are provided with suitable lateral bracing to form light steel" trusses which may be employed in the formation of roof structures in a manner following in some- :lo" respects the ordinary wood construction practice as opposed to the ordinary practice using structural steel trusses. The roof structures formed through the use of the trusses of the present invention are placed at close centers, us-

:(5 ually from 2 to 4 feet apart, with the result that the load of the roof may be so uniformly distributed that the roof structure may be supported on any suitable bearing wall, whereby the present invention dispenses with the necessity usually 4,, found in ordinary structural steel practice of supporting the individualtrusses or columns.

Furthermore, the trusses of the present invention and the roof structures formed thereby reduce the cost of the roof deck-supports or elimir', nate such secondary members altogether. The

cost of secondary roof supports or purlins increases rougnlyin proportion to the spacing of the purlin supportsfor trusses. In accordance with ordinary structural steel practice a large 5 number of web members is customarily used for the purpose of providing a top chord panel point wherever a purlin occurs.- The purpose ofthis practice is to minimize the cost of relieving the top chord of bending stresses. 'In -the case of 55 the present .invention the open web sections or expanded structural members used for the top chords are economically suited to withstanding both direct and bending stresses,,and it is, therefore, feasible to reduce the number of web mem-' bers. This reduction in the numberoi pieces 5 composing the truss greatly reduces fabricating and handling costs.

In a like manner, when thebottom chords oi the truss units are composed of the Webbed structural elements, the bottom chord is able not only 10 to withstand the direct tensile stress under truss action, but also to resist bending stresses imposed whenever a ceiling construction. is attached directly to said bottom of a chord of the truss. Thereby the ceiling construction is reduced'in cost as compared with ordinary structural steel construction for the reason that the close spacing of'the truss units provides ,meansflfor direct attachment of the ceiling to the trusses without the necessity of providingceiling hangers or supplementary steel framing at the ceiling level.

The roof s ructures formed by the trusses of the present invention differ in principle of operation from roof structures heretofore formed through the use of structural steel. In accordg5 ance with the principles of thepresent invention,

the framing of the roof formed by the trusses assembly acts as a unit and theload resisting 35.

properties of the completed roof structure may there y be in r ased a numb Qfi e e erith propertiesjof th tru u al'ira e name In ast practice with tructural steel rponng because of h conc tr ti n ofth lo ds at widely spa d po nts. .Such addi onal ma e a has nqtm t rially assisted, if at all, in increasing the strength of the combined roof structure. I j

The present invention, together with various further objects and advantages thereof will 'best 5 be understood from the following description of the preferred form of the presentinvention.

.In theaccompanying drawings, the preferred forms of trusses and roof structures embodying the present invention are disclosed, in'which 50 Figure, 1 is an elevation of .a preferred form of a unit truss.

{Figure '2 is an elevation of a segment truss embodying the present invention; is

Figure 3 {is a perspective view of a typical roof structure embodying the present invention and utilizing the unit truss and segment truss of Figures 1 and 2, respectively.

Figure 4 is an enlarged fragmentary elevation of a roof structure embodying the present invention.

Figure is an enlarged elevation of the expanded or webbed chord members of the truss.

Figme 6 is a section on the line 6-6 of Figure 5.

Referring to the drawings, in the trusses of the present invention the bottom chord 2 and the top chords 3 and 4 of the truss (Fig. l) are formed of so-called expanded means or equivalent structural elements. The form of the expanded or open web elements used for the chords 2, 3 and 4 is shown in Figures 5 and 6, wherein the beam 2, for example, is illustrated as comprising upper and lower rails 5 and 6 intercon nected by the web-like interior elements 1, the whole constituting a generally I-shaped beam. Such structural elements are usually made by forming a light-weight I-beam in the usual manner, with the separation between the rails 5 and 6 very small compared with that shown, and the material between the rails then punched and the rails 5 and 6 expanded to pull intervening material into the web-like form shown in Figures 5 and 6. While I prefer to use the webbed I-beam members 2,- 3 and 4 which have been formed by the expanded process, it is obvious that the interior elements I might be formed separately from the upper and lower rails 5 and 6 and the same welded together to form a beam. As a result thereof, an I-beam of very light construction can be formed which provides desirable beam properties and an element of exceptionally light weight and structure. The

inner. section of the various web-like I-beams 2,

3 and 4 of the truss are preferably formed by welding the ends of the expanded or web chords to plates '1, 8 and 9. The top and bottom chords of the truss are connected by suitable interior members l0, which may be single angles and which are joined in position by welding to the web sections through the employment of plates ll and I2 where necessary.

The trusses of the present invention may have various desired shapes and contain various manners of arrangement and spacing of the interior members I0. For example, in Figure 2 there is indicated a segment truss having the bottom chord 2a, the top chords 3a and 4a, and the segment chord member l3, and with suitably arranged interior single angle members lfla. Such segment trusses find particular application in the formation of a hipped roof framing.

The roof framings produced in accordance with the present invention may be understood from an example thereof shown in Figures 3 and 4. In Figures 3 and 4 a typical hipped roof framing constructedin accordance with the present invention is illustrated. The roof framing is indicated as supported by a wall framing I4 indicated as likewise formed from the use of the expanded or webbed members, although it is to be understood that the roof framing of the present invention is adapted to be supported by any desired preferred form of wall or framing. A characteristic feature of the present invention is that the framing is so constructed that as distinguished from ordinary structural steel practice the load isdistributed so that the framing may be supported on a bearing wall and the trusses are not required to be individually supported from columns. In the construction of the roof framing a number of truss members I5 are employed, which may be of the type illustrated in Figure 1 of the drawings, and at the hipped portion of the roof, a plurality of suitably sized segment truss members I6 is employed which may follow generally the plan shown in Figure 2. The truss members l5 and I6 are spaced apart a suificiently short distance between centers, such, for example, as 2 to 4 feet, and made of sufficiently light weight so that it is unnecessary to support the individual trusses on columns. Also, as illustrated, when the supporting wall is formed of expanded or webbed beam studs, it is unnecessary even to superimpose the weight of the trusses l5 or IE above such studs I4.

In the roof structure of the present invention the support of the roof in the ceiling from the framing may, for example, be accomplished by purlins I! held by angles l8 to the top chords 3 and 4 of the trusses, and such purlins may be disposed in any suitable positions; that is to say, they may be positioned on the chords between the interior bracing. Thus, the load of the roof may be distributed over the chords in any desired manner. Upon the purlins any desired roof may be built, and I have indicated in Figure 4 the roof completed by diagonal sheathing l9 carrying shingles 20. A further feature of the present invention is the fact that the ceiling may be directly connected to the trusses. For examample, the ceiling may be most readily formed by attaching a metal lath 2| to the bottom chords 2 of the truss and then forming thereon any usual or desired plaster ceiling 22.

Now, referring to Figure 7 of the drawings, I have illustrated a modified method of attaching the sheathing I9 to one of the top chords 2 or 3 of the truss, which method has the advantage of dispensing entirely with the necessity of using the purlins ll. In accordance with the method of roof formation shown in Figure '7, the sheathings l9 are directly connected with the chords of the truss. Various desired means of direct connection may be used, and I have illustrated, for example the form where the top of the chords are provided with holes through which nails 23 are driven into the lower side of the sheathing for holding the same in position.

The novel truss and roof structure of the present invention permits the extension of structural steel work to the building of many structures which heretofore could not be economically formed by structural steel and displaces the use of wood structures and wood framing with considerable advantage in many cases.

While the particular form of the invention herein described is well adapted to carry out the purposes and advantages of the invention, it is to be understood that various modifications and changes may be made all without departing from the principles of the present invention, and the present invention includes all such modifications and changes as come within the scope of the appended claims.

I claim:

1. A unit truss comprising top and bottom chord members each being formed of an I-beam of light-weight construction and having the medial portionthereof of expanded or web form, said chord members being welded together and being connected to form a truss by interior bracing.

2. A-segment truss comprising a bottom chord member, top chord members and a segment chord member, each of said chord members being formed of an I-beam of light-weight formation having their medial portions of expanded or web formation, said chord members being welded together and being interconnected by interior truss forming braces.

3. A roof structure composed of unit trusses formed with interior bracing and outer chords of expanded or web-like I-beam members, said unit trusses having a short spacing between centers whereby to form a roof framing having the capacity to be supported by a bearing wall.

4. A roof structure composed of unit trusses formed with interior bracing and outer chords of expanded orweb-like I-beam members, said unit trusses having a short spacing between centers whereby to form a roof framing having the capacity to be supported by a bearing wall, said trusses supporting purlins distributed over the top chords thereof for forming a roof deck.

5. A roof structure composed of unit trusses formed with interior bracing and outer chords of expanded or web-like I-beam members, said unit trusses having a short spacing between centers whereby to form a roof framing having the capacity to be supported by a bearing wall, the bottom chords of said unit trusses directly supporting the ceiling.

6. A roof structure composed of unit trusses formed with interior bracing and outer chords of expanded or web-like I-beam members, said unit trusses having a short spacing between centers whereby to form a roof framing having the capacity to be supported by a bearing wall, and ceiling lath directly tied to said bottom chords.

'7. A roof structure composed of unit trusses formed with interior bracing and outer chords of expanded or web-like I-beam members, said unit trusses having a short spacing between centers whereby to form a roof framing having the capacity to be supported by a bearing wall, ceiling lath directly tied to the bottom chords of said unit trusses, and purlins distributed over the top chords of said unit trusses.

8. A roof structure composed of closely spaced light-weight metal unit truss members, said unit truss members having their bottom and top formed of expanded or web-like I-beam members, the spacing between said unit truss members being approximately 2 to 4 feet on centers, whereby ceilings may be directly tied to the bottom chord members and secondary roof supporting members rendered unnecessary for the formation of roof decks.

9. In a roof structure, a truss member having top and bottom chord elements each being the medial portion thereof of expanded form and including interior bracing, and a plurality of segmental truss members each also including top and bottom truss members, each of which truss members has top and bottom chord members formed of an I-beam of light-weight construction and the medial portion thereof being of expanded form and including interior bracing.

11. A hip roof structure comprising a truss member forming the apex of the hip of the roof structure and a plurality ,of successively lower height segmental truss members, each of the truss members having top and bottom chord members formed of an I-beam of light-weight construction with the medial portion thereof of expanded form and including interior bracing, sufilcient of said truss members being provided at short spacings apart whereby the roof structure has a capacity to be supported by a bearing wall.

12. A hip roof structure including an addition to a truss member at the apex of the hip, a plurality of suitably sized segmental truss members, each of the truss members being formed with top and bottom chord members of a light-weight I- beam form having expanded medial portions, trusses under the hip of said roof having a space between the centers of between two and four feet whereby to produce a hip roof structure with a sufiiciently distributed'load to have a capacity to be supported by a bearing wall.

13. A hip roof structure comprising a truss member forming the apex of the hip of the roof structure and a plurality of successively lower height segmental truss members, each of the truss members having top and bottom chord members formed of an I-beam of light-weight construction with the medial portion thereof of expanded form and including interior bracing, sufiicient of said truss members being provided at short spacings apart whereby the roof structure has a capacity to be supported by a bear ing wall, and a ceiling supported directly by the bottom chords of said trusses whereby said bottom chords act under compression.

FREDERICK H. RUPPEL. 

